Describe six patients with severe neuropathic pain syndromes with significant benefits on lacosamide therapy.

Trigeminal neuralgia (TN) is a rare, debilitating pain syndrome. It is associated with multiple sclerosis (MS) however most cases are idiopathic. MS has many other associated pain syndromes including dystonic spams. Treatment includes antiepileptic drugs (AEDs); carbamazepine is the most common due to efficacy. However, not all patients respond and side effects limit some patients.

Lacosamide is an AED, typically well tolerated, that works by enhancing the slow inactivation of sodium channels inhibiting repetitive firing of nerves.

Identical female twins with idiopathic TN. Both required high doses of carbamazepine causing significant fatigue. Gabapentin was also prescribed, but severe daily pain from TN continued. Lacosamide, 75mg twice a day, showed near immediate decreased pain and ability to decrease other medications.

MS patient with severe dystonic spasms on right arm and leg, and severe right face and arm pain. Not responsive to carbamazepine, gabapentin, or high doses of baclofen. The face pain improved significantly with lacosamide 100mg twice a day, but painful spasms continued. An increase to 150mg twice a day resolved the face pain, but no change in spasms. She developed urinary retention on 150mg dose.

Two patients with neuromyelitis optica with intermittent daily dystonic spasms previously partially controlled on carbamazepine, one limited in dosing due to hyponatremia and the other limited due to dizziness. Trial of lacosamide with near resolution of painful dystonic spasms.

Patient with stiff person syndrome with severe axial rigidity and pain. A trial of lacosamide significantly reduced rigidity.

Neuropathic pain syndromes, including TN, can be difficult to manage and many require trial of multiple AEDs. Lacosamide may be a safe and effective second or third line treatment for TN and other neuropathic pain syndromes.